Hi,

I'm miserably failing at rigging a very simple thing, I really need some help please.
I say miserably 'cause it's something that would have taken me 5min 15 years ago in another DCC

I'm trying to rig an very basic hexapod. So just a body and 6 legs with IK controls.
Each leg is only 3 bones :

• shoulder only rotate on y axis
  
• upper leg only rotate on x
  
• lower leg only rotate on x
  

I've searched a lot on the web and every single example I can find is the easy way of a ball joint at the shoulder.
But when you want something mechanically "real" (no ball joint) then there's little to no info available.

Tried to fine tune limit/constraint an ikchain with APEX, couldn't figure it out.
Then I tried with kinefx, same thing.

Then I've tried to cut the problem, since I can't find any info on how to limit/constraint an IK chain, by using a lookat on the shoulder, pointing to the IK tip target, but I can't get it to work with a moving body.



I'm almost there, but my problem now is that I'm able to make a lookup pointing to the ik target, I replace the Y position of the target with the shoulder Y value in a rigattributeVop, but it's not enough, when I rotate the body it's not working because I should point to the target projected on a plane (XZ plane of the shoulder bone) and not just replace the Y value.

I'm failing at making the rigvop network that would "project" the target position into the right plane.
I'm also wondering if there isn't a way more straight forward approch to rig this.
If I could lock rotation on the joints of the IKchain, I wouldn't even need the lookat !
There's a node called ConfigureJointLimit ! But it's not doing anything to the IKchain 😦 Seems to be for ragdolls and fullbodyIK.

Not sure if I'm clear enough to describe my issue :/

I'm attaching a hip file of where I'm at now.

Thanks in advance, any help would be much much appreciated, or just pointing my to some related resources..

well, that's not a very popular topic...

I managed with some help to achieve what I wanted to do with the lookat, but it's actually useless since I can't limit the rest of the leg since IKchain can't be limited (what a shame and why???).

So I went the fullbody IK route, with kinefx since APEX FBIK can't have limits. The result is just horrible to animate, nothing to prevent you from going out of bounds...

I can't find any examples online, has anyone ever rigged an hexapod mechanically ?

Have you tried using the multiik?

@tamte helped me out on a related topic [www.sidefx.com], but I'm having the same issue as you: limits on joints don't seem to apply to IK controllers for reasons that aren't clear to me, even when attempting to apply limits directly to the controllers. In my current project, a quadropod drone with basically the same joint setup as yours, I can see rotation limits applying to the target controller, but if I move the controller, every joint will violate its limits to follow the IK controller. From what I can tell, IK overrules limits even when the limits are being set on the IK setup itself.

Adding the IK w/Constraints solver to APEX is still on the TODO list.